Insulating-tube.



E. F. CALLENDER. INSULATING TUBE.

APPLICATION FILED FEB. 9 19M.

Patented Oct. 26, 1915;

UNITED; STATES PATENT OFFICE.

EDWIN F. CALLENDER, GALESIBURG, ILLINOIS, ASSIGNOR F ONE-HALF TO L. BELLE CALLENDER, OF GALESBURG, ILLINOIS.

INSULATING-TUBE.

' Specification of Letters Patent.

Patented Oct. 26, 1915.

'To all whom it may concern:

Be it known that I, EnWIN F. OALLENDER, a citizen of the United States, and a resident of Galesburg, in the county of Knox and State of Illinois, have invented a new and useful Insulating-Tube, of which the following is a specification.

My invention'relates to tubes of that char acter which are usually formed (by molding) from earthenware or porcelain possessed of electric-insulating properties, and which tubes are employedto permit the passage therethrough of current-carrying wires, the tubes per se being first inserted into openings bored through joists, girders, partitions, etc.,. whereby the tube prevents contact of the live wire therewith.

Tubes of this character as heretofore constructed have not been adequate in their rets. One inadequacy is that some of them ave been constructed with their outer surfaces, or at least the body portion, forming a perfect cylinder from. end to end, or of the same cross sectional areas throughout their lengths. So constructed, there was nothing to prevent them from working out of holes slightly too large. And if the openings for their reception were of such circumference that they fitted very snugly therein they were, owing to their frangible character, frequently broken during placement, owing to driving or forcing them thereinto. Broken pieces of the tube are left to remain in the openings, and in pulling the wires the insulation thereon. is frequently .damaged by said broken pieces, to such extent, in fact, that it is utterly unsafe to use the wires. Furthermore, electricians in working on old buildings often find that tubes have fallen out of the holes and that mice in attem ting to pass therethrough have gnawed o the insulation; if the surrounding wood be damp a ground is formed and a fire imminent. The main objection, however, was to All holes bored in resldence wiring are- 5/8that being standard.- The tubes which are almost universally used are somewhat smaller and are intentionally made to fit loosely within said holes. The reas n for thls is that it is impossible to construct the tubes of even diameter and circumference throughout their lengths, i. e., minute imperfections will occur in many, and it would be very expensive to throw away all such. Continued walking on floors will-cause the tubes to vibrate and eventually drop out of the openings. This is conclusively demon strated by the fact that in overhauling old houses electricians find that a large proportlon of the tubes have worked out of the holes and are hanging suspended on the wire, (which provides a runway therefor,) especially if the holes be bored at an inclination downward, as they generally are.

Other tubes have been provided with longltudinal ridges extending throughout their entire lengths. One of thls character cannot be used, 111 ordinary practice, without breaking it, for what very slight taper is present is at the tip only, and a circle described around the heel portionof the ridges is of no greater diameter than one drawn quite close to the tip. Inasmuch as the ridges begin to cut intothe wood as soon as force is applied in placing the tube, the act of forcing it into.the opening will cause the weak tip end to collapse or crumble, because of the sudden shock, the length of the ridges, and the lack of taper thereof. 7 I have stated that the length of the ridges is a factor. This is because as soon as they begin cutting, their cutting edges begin to crumble and the broken-0E particles adhere to the wood and cause the cuts or clefts to fill and bind the ridges tightly, causing such pressure thereon as is almost certain .to crush the tube. And if the hole in the joist be suliiciently large to prevent this, the ridges will have no tendency to bind the tube therein, for their diameter is the same throughout all that portion of the tube which is in contact with the joist.

The main object of my invention is to provide a tube of the character; described which may be forced into frictional, wedging contact with any suitable yielding surface, whereby said tube will be self-contained in the opening provided by such surface, with little or no danger of breaking the tube as may be fully understood I have appended hereto a sheet of drawings showing a preferred and also modified embodiments thereof; and in-which:

Figure l is a perspective View of the preferred construction; Fig. 2, a transverse sectional view. taken'in the line 22in Fig. 1-; Fig. 3, a modification, shown in perspective; Fig. 4, another modification, an end view; Fig. 5, still another modification, shown in perspective; and Figs. 6 and 7, enlarged fragmental details showing respectively an end-(or ooint) view and a plan View of a preferred type or form of fin.

. Coming now to a detailed description of said drawings and referring to the component portions of the tube by distinguishing reference vnumerals, 2 designates a tube formed of suitable plastic material, hardened by drying, baking or burning, and comprising a tubular body 3, an annular bead or head 4, and a suitable number of fins 5, pref- 'is essential, however, that the fins do not extend from end to end of the tube body, for reasons presently stated.-

In the modification shown in Fig. 3 I have illustrated a tube having no bead, but tapered\ gradually from end to end on its outer surface and provided with fins 5.

ter, 2'. 6., co-extensive with its length, I make no claim.

In Fig. 4 I have illustrated another modification, wherein the tube is tapered and provided with an undulating or corrugated face, the ridges of which correspond to the fins 5 shown in the 'principal figures.

In Fig. 5 I have shown the fins as disconnected from the beada space 10 intervening. The fins may be inserts, if preferred. Other modifications which wouldpresent themselves to the skilled artisan, but which fall within the general idea of the invention as defined in the appended claims, may be made. It-will be noted that the rear ends of they fins on the tubes shown in Figs. 1 and 3 rise to a height equal to that of the bead or head 4E-that is to say, a circle-circumscribing said ends of the fins is substantially equal in circumference to the circumference of said bead or head. A minute difference,

as may occur in the process of manufacture, is immaterial.

The advantages gained by making the fins To a tube having fins of this particular characsharply tapered and extending but a relatively short portion of the length of the tube body, (preferably less than one-half,) are: First: The finscommence cutting only after the plane cylindrical portion of the tube has passed through the joist and cleared the opening therein of the cuttings left from the bit. Second: Being sharply and gradually tapered they cut constantly as they progress. Third: Because of being tapered throughout their lengths and cutting as they progress, the forward portion constantly cuts a passage for the oncoming portion, but cuts it gradually. There is no danger, then, of breakage. Fourth: The operator can judge with certainty when the tube has been drivenasufiicient distancethis by merely moving or attempting to move it laterally.

Fifth: That portion of the fins which is in frictional contact with the rear edge of the opening in the joist must of necessity bind against the wood, but against an an ar edge thereof only, whereas in former" bes (the ridges being the same in height throughout or substantially throughout their lengths) the -tipsif they cut at allcut a constantly increasing way for the por' tions which followed, and there was abso- 'lutely no wedging action such as itis evident is present in and one of the prime and essential features of my invention. Sixth: The front end portion of the tuba-being a plane-faced cylinder, thoroughly cleans the 'hole in the joist as it is driven thereinto, thus preparing it for the admission of the points of the fins. It Willb evident that before the fins begin to cut, the fore end the tube will have passed entirely through the ordiriary joist..

Having thus described the nature, objects, purposes and advantages of my invention, I claim as new and desire to secure by Letters Patent the following, 'to-wit:

1. A tube made of frangible insulating material and havin a triangular-fin on its outer surface, said fin terminating approximately midlength of the body of the tube- I length.

2. A tube made of frangible insulating material'having a bead near one of its ends and having a triangular fin tapered toward the end of the tube most remote from said bead, said fin terminating approximately midlength of the body'of the tube and the taper being continuous and regular through-- out its entire length.

3. An article-of the class described made of frangible insulating material and -;comprising a tubular body having a peripheral head which also is tubular, and having a plurality of fins extending each from said head to substantially the midlength of the body, the rear end of each fin being equal in height tothe periphery of said head,each fin being and. being tapered throughout its entire tapered continuously and regularly throughout its length.

4. An article of the class described made of frangible insulating material and comprising a tubular body having a peripheral head which also is tubular, and having a plurality of fins extending each from said head to substantially the midlength of the body, a circle circumscribing the rear ends of said fins being of the same circumference as is the circumference of the head.

5. An article of the class described made of frangible insulating material and comprising a tubular body having an annular head which also is tubular, and having a plurality of continuously and regularly tapered fins the rear ends of which are in contact with said head, a circle circumscribing the rear ends of the fins being of the same circumference as is the said head.

6. An article of the class described made of frangible insulating material and comprising a body which is tubular throughout its length and having an annular head, and having also a plurality of fins extending each from said head to substantially the midlength of the body, the upper edge or top of each fin touching the extreme outer edge or periphery of said head.

In testimony whereof I hereunto sign my name, at Galesburg, Knox county, Illinois, this 2nd day of February, 191%.

EDWVIN F. CALLENDER.

In presence of J. E. MALEY, A. G. STEVENSON. 

